This invention relates to electro-kinetic conversion of electrical energy into fluid flow of an ionizable dielectric medium in which an electro-kinetically produced flow of air is created, the air containing safe amounts of ozone and from which air particulate matter has been substantially removed, and more particularly to portable such units adapted for use in a confined area in which some degree of humidity control is desired.
The use of an electric motor to rotate a fan blade to create an air flow has long been known in the art. Unfortunately, such fans produce substantial noise, and can present a hazard to children who may be tempted to poke a finger or a pencil into the moving fan blade. Although such fans can produce substantial air flow, e.g., 1,000 ft3/minute or more, substantial electrical power is required to operate the motor, and essentially no conditioning of the flowing air occurs.
It is known to provide such fans with a HEPA-compliant filter element to remove particulate matter larger than perhaps 0.3 xcexcm. Unfortunately, the resistance to air flow presented by the filter element may require doubling the electric motor size to maintain a desired level of airflow. Further, HEPA-compliant filter elements are expensive, and can represent a substantial portion of the sale price of a HEPA-compliant filter-fan unit. While such filter-fan units can condition the air by removing large particles, particulate matter small enough to pass through the filter element is not removed, including bacteria, for example.
It is also known in the art to produce an air flow using electro-kinetic techniques, by which electrical power is directly converted into a flow of air without mechanically moving components. One such system is described in U.S. Pat. No. 4,789,801 to Lee (1988), depicted herein in simplified form as FIGS. 1A and 1B. Lee""s system 10 includes an array of small area (xe2x80x9cminisectionalxe2x80x9d) electrodes 20 that is spaced-apart symmetrically from an array of larger area (xe2x80x9cmaxisectionalxe2x80x9d) electrodes 30. The positive terminal of a pulse generator 40 that outputs a train of high voltage pulses (e.g., 0 to perhaps +5 KV) is coupled to the minisectional array, and the negative pulse generator terminal is coupled to the maxisectional array.
The high voltage pulses ionize the air between the arrays, and an air flow 50 from the minisectional array toward the maxisectional array results, without requiring any moving parts. Particulate matter 60 in the air is entrained within the airflow 50 and also moves towards the maxisectional electrodes 30. Much of the particulate matter is electrostatically attracted to the surface of the maxisectional electrode array, where it remains, thus conditioning the flow of air exiting system 10. Further, the high voltage field present between the electrode arrays can release ozone into the ambient environment, which appears to destroy or at least alter whatever is entrained in the airflow, including for example, bacteria.
In the embodiment of FIG. 1A, minisectional electrodes 20 are circular in cross-section, having a diameter of about 0.003xe2x80x3 (0.08 mm), whereas the maxisectional electrodes 30 are substantially larger in area and define a xe2x80x9cteardropxe2x80x9d shape in cross-section. The ratio of cross-sectional areas between the maxisectional and minisectional electrodes is not explicitly stated, but from Lee""s figures appears to exceed 10:1. As shown in FIG. 1A herein, the bulbous front surfaces of the maxisectional electrodes face the minisectional electrodes, and the somewhat sharp trailing edges face the exit direction of the air flow. The xe2x80x9csharpenedxe2x80x9d trailing edges on the maxisectional electrodes apparently promote good electrostatic attachment of particular matter entrained in the airflow and help airflow. Lee does not disclose how the teardrop shaped maxisectional electrodes are fabricated, but presumably they are produced using a relatively expensive mold-casting or an extrusion process.
In another embodiment shown herein as FIG. 1B, Lee""s maxisectional sectional electrodes 30 are symmetrical and elongated in cross-section. The elongated trailing edges on the maxisectional electrodes provide increased area upon which particulate matter entrained in the airflow can attach. Lee states that precipitation efficiency and desired reduction of anion release into the environment can result from including a passive third array of electrodes 70. Understandably, increasing efficiency by adding a third array of electrodes will contribute to the cost of manufacturing and maintaining the resultant system.
While the electrostatic techniques disclosed by Lee are advantageous to conventional electric fan-filter units, Lee""s maxisectional electrodes are relatively expensive to fabricate. Increased filter efficiency beyond what Lee""s embodiments can produce would be advantageous, especially without including a third array of electrodes. Further, Lee""s system does not provide for changing the moisture content of the output flow of air, and does not lend itself to being fabricated in a small form factor, for example hand holdable.
While a Lee-type system may be useful in a room, it does not lend itself to portability, for example for use in a confined relatively small area such as the seating compartment of a motor vehicle or an airplane.
Thus, there is a need for a portable electro-kinetic air transporter-conditioner that provides improved efficiency over Lee-type systems, without requiring expensive production techniques to fabricate the electrodes. Preferably such a conditioner should function efficiently without requiring a third array of electrodes. Such a conditioner should permit user-selection of safe amounts of ozone to be generated, for example to remove odor from the ambient environment, and should be implementable in a hand held form factor so as to be portable. Further, such a conditioner should permit increasing the moisture content of the output airflow.
The present invention provides a method and portable apparatus for electro-kinetically transporting and conditioning air.
The present invention provides a preferably portable electro-kinetic system for transporting and conditioning air without moving parts. The air is conditioned in the sense that it is ionized and contains safe amounts of ozone, and, optionally, can benefit from augmented moisture content or aromatic content. Indeed users who are asthmatics may wish to provide the invention with an asthma inhalant that is added to the outflow of clean air, for their personal benefit.
Applicants"" electro-kinetic air transporter-conditioner includes a housing with at least one vent through which ambient air may enter, and an ionizer unit disposed within the housing. The ionizer unit includes a high voltage DC inverter that boosts low voltage (e.g., perhaps 6 VDC to about 12 VDC) to high voltage DC, and a generator that receives the high voltage DC and outputs high voltage pulses. The high voltage pulses are perhaps 10 KV peak-to-peak, although an essentially 100% duty cycle (e.g., high voltage DC) output could be used instead of pulses. The unit also includes at least one and preferably two electrode assembly units, each unit comprising spaced-apart first and second arrays of conducting electrodes coupled between the positive and negative output ports of the high voltage generator. Preferably at least one moisture-containing member is disposed adjacent a downstream region of each second-array electrodes so as to increase humidity of the output airstream.
Preferably two electrode assemblies are used, in which each assembly is formed using first and second arrays of readily manufacturable electrode types. In one embodiment, the first array comprises wire-like electrodes and the second array comprises xe2x80x9cUxe2x80x9d-shaped electrodes having one or two trailing surfaces. In a preferred, even more efficient embodiment, each first array includes at least one pin or cone-like electrode and the second array is an annular washer-like electrode. The electrode assemblies may comprise various combinations of the described first and second array electrodes. In the various embodiments, the ratio between effective radius of the second array electrodes to the first array electrodes is at least about 20:1.
The high voltage pulses create an electric field between the first and second electrode arrays in each electrode assembly. This field produces an electro-kinetic airflow going from the first array toward the second array, the airflow being rich in preferably a net surplus of negative ions and in ozone.
Ambient air including dust particles and other undesired components (germs, perhaps) enter the housing through the input vent, and ionized clean air (with ozone) exits through openings on the downstream side of the housing. When the moisture-containing member is wet, the exiting air flow can have increased humidity.
The dust and other particulate matter attaches electrostatically to the second array (or collector) electrodes, and the output air is substantially clean of such particulate matter. Further, ozone generated by the present invention can kill certain types of germs and the like, and also eliminates odors in the output air. Preferably the transporter operates in periodic bursts, and a control permits the user to temporarily increase the high voltage pulse generator output, e.g., to more rapidly eliminate odors in the environment.
In one embodiment, the system includes an internal battery power supply and can be suspended by a cord from a user""s neck, with the outflow airstream directly generally upward toward the user. This embodiment is especially useful in a confined area where the air might be stale or germ-laden, for example the seating compartment of an airline, or a bus. A similar embodiment can be used within and powered from the power supply of a motor vehicle, for example, from the cigarette lighter accessory plug of an automobile or truck. This embodiment includes an electronic timer that causes the system to operate for a predetermined time (perhaps half an hour) each time the power supply is turned-on, with an option for the user to cause the system to operate more than once per system turn-on. Alternatively a motion sensor switch comprising a sound or force detecting transducer and movable objects can turn-on the system whenever the vehicle in moving sufficiently to agitate the movable objects such that their vibration-motion is transducer detected.